The invention relates to a centered double universal joint, especially for driving, or for drives in, agricultural implements and tractors.
DE 39 21 242 C1 (which is the priority document for U.S. Pat. No. 4,997,407) describes a centered double universal joint with two outer joint yokes articulatably connected by a cross member to two inner joint yokes to form part of a housing. An annular recess is formed in the housing. A guiding disc is radially adjustably supported in the housing. Floating annular guiding plates sandwich the guiding disk. The guiding disc includes a centrally arranged guiding projection. The projection projects from both sides of the guiding disc. The outer joint yokes, whose yoke arms are connected to one another by a bridge, each include a journal projection. The journal projection includes a spherical face and is pivotably supported in a bore of the central guiding projection of the guiding disc. The cross members each include lubricating channels which are used to lubricate rolling bearings. The rolling bearings support the cross member in the yoke arms. The lubricating channels are each connected to lubricant guiding means in the journal projections. The channels open into the bore of the central guiding projection of the guiding disc. At least one radially extending lubricant channel is provided in the guiding disc. The channel connects the bore in the central guiding projection to the annular recess. It is thus possible to convey lubricant from a lubricating nipple, provided at the cross member, into the annular recess. The disadvantage, however, is that at high rotational speeds of the double universal joint, the lubricant is thrown radially outwardly as a result of the centrifugal forces. This has an adverse effect on the lubrication of the guiding disc and the guiding plates.
DE 28 02 572 C2 (which is the priority document for U.S. Pat. No. 4,257,243) discloses a centered double universal joint wherein a guiding disc, articulatably connected via centring projections to outer joint yokes, is radially adjustably guided in an annular recess. The housing includes a lubricating nipple which is directly connected to the annular recess by a lubricant channel. Thus, the rolling bearings of the cross members and the annular recesses are lubricated independently of one another. Accordingly, the lubricant is pressed radially outwardly by the centrifugal forces.
It is an object of the present invention to provide a centered double universal joint with a guiding disc that improves lubrication of the guiding disc.
In accordance with the invention, a centered double universal joint includes a first outer joint yoke with first outer yoke arms. A first bridge connects the first outer yoke arms to one another. A first centring mechanism is associated with the first bridge.
A first inner joint yoke is provided with first inner yoke arms. A first cross member articulatably connects the first outer yoke arms by rolling bearings to the first inner yoke arms. The inner yoke arms include a first lubricant supply to lubricate the rolling bearing.
A second outer joint yoke is provided with second outer yoke arms. A second bridge connects the second outer yoke arms to one another. A second centring means is associated with the second bridge. A second inner joint yoke is provided with second inner yoke arms. A second cross member articulatably connects the second outer yoke arms by rolling bearings to the second inner yoke arms. The second inner yoke arms includes a second lubricant supply to lubricate the rolling bearings.
A guiding disc defines a longitudinal axis. The guiding disc has a first central centring projection articulatably connected to the first centring mechanism of the first outer joint yoke. The guiding disk has a second central centring projection articulatably connected to the second centring mechanism of the second outer joint yoke. Guiding faces guide the guiding disc in an annular recess of a housing. The annular recess is delimited by a first radially extending annular sealing face and by a second radially extending annular sealing face. The guiding faces of the guiding disc are radially displaceably guided relative to the sealing faces. The annular recess is closed on the radial outside and open on the radial inside.
A first lubricating groove is provided in the first sealing face. The first lubricating groove extends coaxially relative to the longitudinal axis of the guiding disc. The first lubricating groove is arranged near the inner diameter of the annular recess. The first lubricating groove is connected to the first lubricant supply of the first cross member.
A second lubricating groove is provided in the second sealing face. The second lubricating groove extends coaxially relative to the longitudinal axis of the guiding disc. The second lubricating groove is arranged near the inner diameter of the annular recess. The second lubricating groove is connected to the second lubricant supply of the second cross member. The first inner joint yoke and the second inner joint yoke form part of the housing.
An advantage of this design is that, due to the first lubricating groove and the second lubricating groove each provided in one of the sealing faces, the sealing faces are directly lubricated Lubricant is introduced directly into the region between the sealing faces and the respective guiding face when the guiding disc is guided directly in the annular recess and the guiding faces of the guiding disc are in direct contact with the sealing faces of the annular recess. When the guiding disc is radially displaced, the guiding faces are lubricated over the largest possible area due to the lubricating grooves being arranged near the inner diameter of the annular recess.
According to a preferred embodiment, annular guiding plates are arranged on both sides of the guiding disc in the annular recess. The outer diameter of the guiding plates is greater than the inner diameter of the annular recess and smaller than the greatest diameter of the annular recess. The inner diameter of the guiding plates is greater than the outer diameter of the guiding projections of the guiding disc and smaller than the outer diameter of the guiding disc. In this embodiment, lubricant is introduced directly, via the lubricating grooves, into the region between a lubricating groove and a guiding face of the respective guiding plate.
According to one embodiment, a first lubricant guiding means is provided in the housing to connect the first lubricant supply of the first cross member to the first lubricating groove. A second lubricant guiding means is provided in the housing to connect the second lubricant supply, of the second cross member, to the second lubricating groove.
Accordingly, it is possible to avoid providing separate lubricating nipples for the lubricating grooves and for lubrication of the rolling bearings of the cross members. The lubricant guiding means make it possible for one cross member and one lubricating groove to form one circuit for lubricating purposes. Thus, during lubrication of the cross member, the lubricating groove is likewise supplied with lubricant at the same time.
The housing includes a circumferential groove to rotatingly receive a protective device. The protective device extends coaxially relative to the longitudinal axis. The recess is connected to one of the lubricating grooves to prevent rotating parts of the double universal joint from being touched. By connecting the circumferential groove to one of the lubricating grooves, the circumferential groove is also incorporated in the lubrication circuit.
Accurate control of the two double universal joints and a long service life are achieved at the guiding disc by providing a cylindrical bearing bore which extends coaxially relative to the longitudinal axis through the first centring projection and the second centring projection. The first centring means and the second centring means each include a bearing journal which extends coaxially relative to an axis of rotation of the respective outer joint yoke.
A bearing ball in the form of a spherical layer is provided per bearing journal. The bearing ball is positioned on the bearing journal via a through bore. The bearing ball is held at least axially relative to the axis of rotation. The bearing ball has a spherical outer face.
A bearing race is provided per bearing ball. The bearing race supports the outer face of the bearing ball in a corresponding hollow-spherical bore. The bearing race has a cylindrical outer face by means of which the bearing race is axially adjustably positioned in the cylindrical bearing bore of the guiding disc.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.